Electric-instrument contact



M: c. COSGRAY.

ELECTRIC INSTRUMENT CONTACT. APPLICATION FILED DEC. H, 1919.

Patented Feb. 15,1921;

UNITED STATES PATE roFFlcs.

MARK C. COSGRAY, OF SANDUSKY, OHIO, ASSIGNOR TO THE MATTHEWS ING COMPANY, OF SANDUSKY, OHIO, A CORPORATION OF OHIO.

ELECTRIC-INSTRUMENT CONTACT.

Specification of Letters Patent.

Patented Feb. 15, 1921.

Application filed December 11, 1919. Serial No. 344,215. v

' State of Ohio, have invented a certain new and useful Electric-Instrument Contact;

and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanyin drawlngs, and to the characters of re erence marked thereon, which form a part of this specification.

My invention has for its object to provide a meansfor closing and opening a circuit. It particularly has for its object to provide such a means in an instrument which has delicate mechanism for causing the performance of its operations. It provides a means whereby a circuit may be closed and opened without drawing an arc and is particularly applicable to structures where the circuit closing and opening is performed by a slow movlng contact. By my invention the circuit is not only closed quickl but is also opened quickly to prevent t e arcing which occurs in both operations but is much greater during the opening of the circuit by the instrument. ,It also provides means for making a good contact. x The invention may be contained in instruments of different forms. To illustrate a practical application of my invention I have selected a mechanism as an illustration of embodiments of my invention and shall describe it hereinafter.

comp-anying drawings. 'This portion contains my invention and also shows its application to such an instrument.

In the drawings, Figure 1 illustrates the. dial or face of an ampere hour meter which has been selected as an example of structure containing the invention and which is commonly used to indicate the charge contained in the storage battery, the instrument being connected in the circuit of the storage battery and the source of electric current used for charging the storage battery and also the circuit of the load that may be carried by the battery. Fig. 2 illustrates an enlarged edge view of the portion of the device illustrated in Fig. 1. Fig. 3 illus- A portion of the instrument selected is illustrated in the actrates a sectional View looking from the axis of the dial. ig. 4 illustrates a top view, the pointer of the instrument being shown in position different from that' in which it 1s located in F igs. 2 and 3. Fig. 5 is an edge view of the parts shown in Fig. 4, and Fig. 6 1s a sectional view looking from the axis of the dial showing the movable contact in circuit closin position.

1, Fig. 1, is the ace or dial of the ammeter which is provided with the usual pointer or indicator 2. Beneath the pointer is located an elastic arm 3 which forms one terminal of the circuit that is closed through the arm and consequently the arm 3 forms a movable contact. The pointer 2 and the arm 3 are moved by any suitable mechanism which forms no part of my invention. The instrument is also provided with a fixed contact with which the contact arm 3 makes contact at some point or condition of charge of the battery or some measurement of current quantity indicated by the ammeter. To prevent arcing between the fixed contact and the arm 3 which moves slowly over the dial,

in the path of the end of the resilient arm- 3 and so that the lower end of the flange 5 is located slightly below the end of-the .arm

3. The flange 5 will thus engage the arm 3 when the arm is moving in one direction so as to raise the arm 'as its movement continues in that direction until the arm passes over the upper end of the flange 5. The fixed contact, which coacts with the movable contact 3 to complete the circuit, is located below the upper end of the flange 5. The circuit is then closed between the movable contact and the fixed contact.

By my invention is provided the fixed contact or anvil contact 6 which is suitably supported and extends up through the dial to receive the end of the arm 3 when it passes from the upper end of the flange 5. The nose of the anvil contact 6 is located just below the upper end of the flange 5 and ex-v tends to a point very close to the upper end of the flange 5 and so that the arm 3 may pass beneath the upper end of the flange 5 as it moves in a reverse direction to that in which it moved when it passed up the flange 5. The upper surface or edge of the anvil contact 6, particularly the nose of the anvil contact, is thus located a little more than the thickness of the end of the arm 3 beneath the upper end of the flange 5 to permit the return of the arm 3 beneath the flange 5. By this arrangement a good contact is made by reason of the fact that the arm 3 is deflected from its normal position by the operation of the flange 5 and held to substantially this deflected position by the anvil contact 6 so that the arm 3 presses against the anvil contact with a pressure proportionate to this deflection by reason of its elasticity. ()wing to the long slant of the inclined flange 5 this deflection from the normal may be made considerable and consequently the pressure of the arm 3 on the contact 6 is considerable. In instruments of this character it is important that good contacts may be made particularly at the point where it is customary to recharge a battery.

The contact is usually connected with a controlling means for starting an internal combustion engine that operates a generator to charge the battery or it is connected with a controlling means that connects the battery with a source of electrical energy. Con- 'sequently it is important that a perfect connection be made at this point, otherwise the battery will become entirely discharged to the great injury of the battery. This applies particularly to ampere-hour-meters but the deflecting means and the raised contact may be used in other instruments to insure certainty of electrical connection. The upper end of the anvil contact 6 terminates in the nose 7 which is formed by the undercut portion 8 of the contact. When, therefore, the end of the arm 3 moves in the reverse direction, the end of the arm 3 will pass off of the nose and by reason of the tension to which it is subjected by reason of the deflection, will be quickly separated from the anvil contact 6. Thus arcing is prevented not only at the time that the contact is made but also at the time that the contacts separate. The anvil contact thus may be connected to a device having considerable self-induction as the break is made with the quickness of the movement of the spring arm which is subject to the tension due to the deflection of the spring from the normal, that is due to the difference in height of the spring above the face of the meter when in the contact and away from the contact. Arcing will thus be prevented upon the separation of the contacts when the arm 3 thus eaves the fixed contact.

The upper surface of the anvil contact 6 slopes toward the face of the dial which permits the arm 3 to gradually recede from its raised position relative to the face of the dial provided the forward movement of the pointer 2 is continued. This also causes the end of the arm 3 to be gradually raised if the pointer passes the anvil contact 6 and is-subsequently returned over the contact 6. This condition may occur, though it is exceptional particularly where the form of contact shown in the figures is used, where there is no response in the apparatus to the closing of the contacts 3 and 6 and where in a subsequent operation the pointer 2 is caused to move in the reverse direction.

I claim:

1. In an electric indicating instrument, a

resilient contact movable over the face and normally located in spaced relation with respect to the face of the instrument, means located in the path of the resilient contact for deflecting the contact from its normal position relative to the face of the instrument, a fixed contact for receiving the resilient contact from the said means and maintaining the resilient contact in a position deflected from the normal.

2. In an electric indicating instrument, a resilient contact movable over the face and normally located in spaced relation with respect to the face of the instrument, means located in the path of the resilient contact for deflecting the contact from its normal position relative to the face of the instrument, a fixed contact having a laterally extending edge located in spaced relation to the said means to hold the said resilient contact deflected from its normal position and permit the return of the movable contact with a quick movement to the normal.

3. In an instrument, a resilient contact movable over the face of the instrument, a fixed contact having a sloping side to raise the said resilient contact and to sharply break the connection between the contacts when moving in one direction, means for raising the resilient contact to above the fixed contact when the resilient contact is moving in the other direction.

A. In an instrument, a resilient contact movable over the face of the instrument, a

fixed contact having an edge extending lat- 5. In an instrument, a resilient contact movable over the face of the instrument, a fixed contact having an edge extending laterally and in the path of the end of the resilient contact and a sloping side extending from the face of the instrument to the said edge to raise the said resilient contact and to sharply break the connection between the cont-acts when the resilient contact is moving in one direction, a member having a sloping surface extending from near the face of the instrument to above the edge of the fixed contact to move the resilient contact to a point above the fixed contact when the resilient contact is moving in the other direction, the end edges of the sloping surface of the said member being located one in spaced relation to the first contact and the other in spaced relation relative to the face of the instrument to direct the end of the resilient member on the sloping surface of the member and on to the fixed contact when it is going in one direction and below the sloping surface when it is going in the other direction. In testimony whereof I have hereunto signed my name to this s ecification,

MARIG COSGRAY. 

